package com.ZhuBaker.github;

import java.io.ByteArrayInputStream;  
import java.io.ByteArrayOutputStream;  
import java.io.File;  
import java.io.FileInputStream;  
import java.io.FileOutputStream;  
import java.io.InputStream;  
import java.io.OutputStream;  
import org.bouncycastle.util.encoders.Base64;
/**  
 * <p>  
 * BASE64编码解码工具包  
 * </p>  
 * <p>  
 * 依赖javabase64-1.3.1.jar  
 * </p>  
 *   
 * @author IceWee  
 * @date 2012-5-19  
 * @version 1.0  
 */  
public class Base64Utils {  
  
    /**  
     * 文件读取缓冲区大小  
     */  
    private static final int CACHE_SIZE = 1024;  
      
    /**  
     * <p>  
     * BASE64字符串解码为二进制数据  
     * </p>  
     *   
     * @param base64  
     * @return  
     * @throws Exception  
     */  
    public static byte[] decode(String base64) throws Exception {  
        return Base64.decode(base64.getBytes());  
    }  
      
    /**  
     * <p>  
     * 二进制数据编码为BASE64字符串  
     * </p>  
     *   
     * @param bytes  
     * @return  
     * @throws Exception  
     */  
    public static String encode(byte[] bytes) throws Exception {  
        return new String(Base64.encode(bytes));  
    }  
      
    /**  
     * <p>  
     * 将文件编码为BASE64字符串  
     * </p>  
     * <p>  
     * 大文件慎用，可能会导致内存溢出  
     * </p>  
     *   
     * @param filePath 文件绝对路径  
     * @return  
     * @throws Exception  
     */  
    public static String encodeFile(String filePath) throws Exception {  
        byte[] bytes = fileToByte(filePath);  
        return encode(bytes);  
    }  
      
    /**  
     * <p>  
     * BASE64字符串转回文件  
     * </p>  
     *   
     * @param filePath 文件绝对路径  
     * @param base64 编码字符串  
     * @throws Exception  
     */  
    public static void decodeToFile(String filePath, String base64) throws Exception {  
        byte[] bytes = decode(base64);  
        byteArrayToFile(bytes, filePath);  
    }  
      
    /**  
     * <p>  
     * 文件转换为二进制数组  
     * </p>  
     *   
     * @param filePath 文件路径  
     * @return  
     * @throws Exception  
     */  
    public static byte[] fileToByte(String filePath) throws Exception {  
        byte[] data = new byte[0];  
        File file = new File(filePath);  
        if (file.exists()) {  
            FileInputStream in = new FileInputStream(file);  
            ByteArrayOutputStream out = new ByteArrayOutputStream(2048);  
            byte[] cache = new byte[CACHE_SIZE];  
            int nRead = 0;  
            while ((nRead = in.read(cache)) != -1) {  
                out.write(cache, 0, nRead);  
                out.flush();  
            }  
            out.close();  
            in.close();  
            data = out.toByteArray();  
         }  
        return data;  
    }  
      
    /**  
     * <p>  
     * 二进制数据写文件  
     * </p>  
     *   
     * @param bytes 二进制数据  
     * @param filePath 文件生成目录  
     */  
    public static void byteArrayToFile(byte[] bytes, String filePath) throws Exception {  
        InputStream in = new ByteArrayInputStream(bytes);     
        File destFile = new File(filePath);  
        if (!destFile.getParentFile().exists()) {  
            destFile.getParentFile().mkdirs();  
        }  
        destFile.createNewFile();  
        OutputStream out = new FileOutputStream(destFile);  
        byte[] cache = new byte[CACHE_SIZE];  
        int nRead = 0;  
        while ((nRead = in.read(cache)) != -1) {     
            out.write(cache, 0, nRead);  
            out.flush();  
        }
        out.close();  
        in.close();  
    }  
      
      
}  